Gravity Survey for Sedimentary Basin Mapping in the Benue Trough

This study conducts a ground gravity survey to map sedimentary basin geometry and crustal structure in a section of the Benue Trough, North Central Nigeria. The Benue Trough is Nigeria's most important onshore sedimentary basin for solid mineral resources, hosting coal, limestone, iron ore, barite, and lead-zinc deposits within its Cretaceous sequence. Accurate knowledge of basin depth, sub-basin structure, and basement relief is essential for targeting mineral exploration and understanding hydrocarbon potential in the southern portion of the trough. This study re-processes and extends a grid of ground gravity measurements in parts of Benue and Nasarawa States, supplemented by 45 new gravity stations at 2-kilometre spacing on critical profiles. Corrections for latitude, free air, Bouguer slab, and terrain effects are applied to compute the Bouguer anomaly. Regional-residual separation is performed using polynomial fitting and upward continuation. The residual Bouguer anomaly is interpreted using spectral depth estimation and 2D forward modelling constrained by available well data. Findings reveal a northeast-trending gravity low of 28 milligal amplitude coinciding with the deepest portion of the basin, interpreted as a depocentre with sediment thickness potentially exceeding 6 kilometres. Two gravity highs flanking the central low are attributed to basement upwarps that may control the distribution of barite veins documented in the geological literature. The study contributes an updated basin geometry model for resource exploration planning in the central Benue Trough.

Keywords: gravity survey, Benue Trough, sedimentary basin, Bouguer anomaly, basement relief.